In recent decades, online learning technology has made significant progress in secondary and higher education, corporate trainings, and professional development. Typical online learning applications in use today are course management systems, homework management systems, assessment management systems, tutoring applications, and hybrids of the former systems.
Course management systems typically focus on providing tools for instructors to deliver course information and course material online and for learners to access course information and online learning content. Homework management systems normally have similar course management functions as a course management system, but provide more features in assignment management for online quizzing and practice. Most of homework management systems use one or more internal or external quiz engines to deliver and grade various online assignments.
Typical assessment management systems focus more on assessing learner's learning status. Such systems use a variety of assessment methodologies ranging from summative assessment, formative assessments, to adaptive assessment. These assessment methodologies largely determined specifically their content format, assignment creation, assessment delivery, and results grading. In recent years, a clear trend is to link assessment more closely with learning, and has gained significant success in practice with many formative assessment systems.
To date, online learning tutoring systems have a much smaller user base in e-learning comparing with course management systems, homework management systems, and assessment management systems. Most tutoring systems fit into the so called intelligent tutoring systems (ITS) that attempt to provide one-to-one tutoring experiences to help learners in their study.
Most of today's ITS systems tries to provide detailed, step-by-step practice-based instructions to help learner in problem solving or skill building. Some ITS systems try to establish learning environments close to certain specific teaching and learning models in order to better utilize learner's learning behavior to tailor strategies and methods to provide more explanations, examples, demonstration, and practice exercises. Some other ITS systems focus on specific knowledge domain and build intelligence and business logics deeply into their assessment and learning content, similar to what many adaptive assessment systems have done. At the same time, without a suitable ITS, to make up the gap between practice, assessment, and learning assistance, some of the learning management systems add on tutoring features by adding logic rules in quiz content and grading mechanisms to provide certain context specific guidance and help.
Main challenges that today's ITS systems face are also rooted in limitations and risks associated within themselves:                1) Are limited to specific knowledge domain or even a specific course subject and cannot support a wide range of subjects and topics;        2) Are limited to specific teaching and learning methodology and cannot effectively integrated with instructor and learners daily teaching and learning activities;        3) Impose high cost for content development due to the need of system specific content and cannot accommodate or reuse existing teaching and learning content or content in different media format or platform;        4) Impose high risk and cost in adoption due to most ITS systems are self-enclosed systems that require users to migrate from existing adopted systems or learn to use a new system;        5) Offer limited content, assessment, and learning assistance and do not provide daily learning assistance to their users.        6) Are inflexible to support curriculum customization.        
The present invention shares with previous ITS systems in concepts of interactive and personalized learning, online learning, and in-time and context specific feedback. The present invention uses new knowledge model and algorithms for knowledge diagnosis and tutoring. The present invention overcomes many limitations of previous ITS systems. The present invention can be implemented for a wide spectrum of knowledge domain, supports different teaching and learning styles, allow easy curriculum customization, does no need of recreate system specific assessment and learning content, can work with other learning management systems, and can be used by instructors and learners in their daily activities.